Using this item starts a 5 minute cooldown on this trinket, and a 1 minute cooldown on other guardian pet trinkets (such as the other mechanical dragonling type trinkets, Defender of the Timbermaw, etc). This means that there is still some value in keeping older dragonling trinkets after creating new ones.

Mithril Mechanical Dragonlings are now always level 50 instead of scaling with the engineer's skill.[1]

Engineering Dragonlings now have a 20 minute cooldown instead of 1 hour

Patch 1.4.0 (2005-05-05): The level of the Mechanical Dragonlings now scale with your engineering skill, so they will be always useful against enemies. Their damage and health has remained the same.

Patch 1.3.0 (07-Mar-2005): Mechanical Whelps have been boosted by five levels in order to be effective longer. Their damage has been slightly decreased to compensate for the additional damage that would have occurred with the change.